WW2 Anti Slew/Inertia Switch Help

Hi Ewan,

Would you have one these Inertia Switches left?

Thank you for your answer.

Mickael

Mate, you know my kids would simply turn around and belt me 🙂 Thanks for the description though, makes a lot of sense and good to know I have pretty much the complete system including the extinguishers (though one is still full of the nasty stuff, something to tackle down the track…)

Fire suppression system

In the Mosquito both switches are mounted one above each other forward of the firewall, for shorter wiring runs.

Inertia switch.
The grandmother of modern automotive crash impact/airbag switches. Recognisable by the setting/testing knob. Inside is a pendulum held in a cup. Hold your left palm up and open, this is the cup. Place your right fist down in the cup, this is the pendulum. Approach your kid playing up after eating 18 Easter eggs with this hand arrangement and punch the kid. Your right fist will slip off the cup at a predetermined ‘moment of inertia’. The cup rests on one end of a tiny see-saw. As the pendulum is off the cup the see saw springs up, closing an electrical contact linked to the fire extinguishers. The switch is positioned with the pendulum acting in the direction of flight, so that when you rapidly decellerated, it would do its stuff. I do not think Japanese Kamikazes had these switches, but the sushi would have come out of their mouth under similar principles.

Gravity Switch.
Electrically linked to the undercarriage up/down senders, and only worked when u/c was down, ie you were intending to land, not doing a victory roll above your mates. Imagine a drunk sitting at a bar. His head is gently nodding forward (your are in flight, going up and down, causing a mechanism to go up and down, but this is restained by a damping device, like a buddy holding the drunk on his stool). Suddenly the drunk’s head hits the bar. ( while landing, you dig your wingtip in, and flip upside down). Again, at this predetermined moment of inertia an electrical contact is closed, triggering the fire extinguishers.

These two switches were linked to a third type, the temperature (flame)switch mounted on the engine firewall and near the carburettor. These had a miniscule charge that detonated in the presence of heat that released a pin otherwise holding back an electrical contact.

I know all this from pg 146 of ‘Understanding Aircraft Components by Q & A 1943 and pulling apart a few to see the ‘cup & fist’ and ‘drunk at the bar’.
I have a complete system for a Mosquito, I just need someone to lend me a Mosquito so we can 633 it into the ground and see how it all works.
Failing that I think they are a prudent investment for when my kid becomes an 18 year old in his first car.

Yes I believe so, one is for forward crashing (for want of a better term) and the other is for sideways (i’m guessing maybe one u/c up landing) – it’s hooked into the flame switches on the firewalls that kick the fire extinguisher system in – this is based on my limited knowledge and viewing of original Graviner adverts, so if I’m well off the mark, my apologies !

Is this the same as what is called a crash switch, they cut electrical power in the event of a moment of high ‘G’ due to an accident but can be set off in a heavy landing, the lever would be used to re set it if it had tripped in the heavy landing instance.

Richard

thread bump two or so years on 🙂

During this week I was sent a pic of one of the M.1.1 units used in a Martinet, I had been told previous that they were used in Beauforts, so this was news and a suprise.

Still havent worked out just why there were so many variants, and why some had levers on the side and others not – and why some are called gravity switches and others inertia switches. Yes I’m full of questions, probably something to do with having easter eggs for brekky with the kids 😉

Anyone able to help with any info I’d be really grateful

Cheers

Ewan